PARALYTIC POLIOMYELITIS IN ROMANIA, 1984-1992 - EVIDENCE FOR A HIGH-RISK OF VACCINE-ASSOCIATED-DISEASE AND REINTRODUCTION OF WILD-VIRUS INFECTION

Although poliomyelitis due to wild-virus infection has virtually disap peared from Romania, with no cases having been documented between 1984 and 1989, vaccine-associated paralytic poliomyelitis has been reporte d at very high rates for over two decades. In November 1990, to decrea se the risk of vaccine-associated paralytic poliomyelitis, oral poliov irus vaccine produced in Romania was replaced by imported oral vaccine made by a Western European manufacturer. To better quantify the risk of vaccine-associated paralytic poliomyelitis and the impact of the ch ange in vaccine manufacturer, the authors reviewed clinical, epidemiol ogic, and laboratory data on poliomyelitis cases that occurred in Roma nia from 1984 to 1992. Poliovirus isolates were characterized at the U S Centers for Disease Control and Prevention. During the period 1984-1 992, 132 confirmed cases of paralytic poliomyelitis were reported in R omania, of which 13 were classified as wild-virus-associated, 93 as va ccine-associated, and 26 as ''of unknown origin.'' Wild type 1 poliovi rus was isolated during 1990-1992 from nine of 13 (69%) cases in an ou tbreak that occurred primarily among undervaccinated gypsy children. V accine-associated cases were epidemiologically and virologically disti nct from wild-virus cases. Of the 93 vaccine-associated cases, 45 chil dren were recipients and 48 were contacts. The overall risk of vaccine -associated paralytic poliomyelitis in Romania (I case per 183,000 dos es of oral poliovirus Vaccine distributed) was 14-fold higher than the risk in the United States. The risks of recipient vaccine-associated paralytic poliomyelitis related to the first dose of oral vaccine were similar for Romanian and imported Vaccine (1 case per 95,000 doses an d 1 case per 65,000 doses, respectively), as were the total risks of v accine-associated paralytic poliomyelitis. These findings definitively demonstrate a substantially elevated risk of vaccine-associated paral ytic poliomyelitis in Romania which was not affected by a change in or al poliovirus vaccine manufacturer.